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Date:   Fri, 22 Sep 2023 08:19:18 +0100
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Subject: Re: [PATCH v1 2/8] powerpc: hugetlb: Convert set_huge_pte_at() to
 take vma
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To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>,
        Nicholas Piggin <npiggin@gmail.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <muchun.song@linux.dev>,
        SeongJae Park <sj@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Uladzislau Rezki <urezki@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Peter Xu <peterx@redhat.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>
Cc:     "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
        "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
        "sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
References: <20230921162007.1630149-1-ryan.roberts@arm.com>
 <20230921162007.1630149-3-ryan.roberts@arm.com>
 <9864a7eb-004d-14c6-c2bd-bb9333fe67be@csgroup.eu>
 <0958d813-15f8-5ed5-1e20-08b8feb465ad@csgroup.eu>
From:   Ryan Roberts <ryan.roberts@arm.com>
In-Reply-To: <0958d813-15f8-5ed5-1e20-08b8feb465ad@csgroup.eu>
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On 22/09/2023 07:44, Christophe Leroy wrote:
> 
> 
> Le 21/09/2023 à 20:43, Christophe Leroy a écrit :
>>
>>
>> Le 21/09/2023 à 18:20, Ryan Roberts a écrit :
>>> In order to fix a bug, arm64 needs access to the vma inside it's
>>> implementation of set_huge_pte_at(). Provide for this by converting the
>>> mm parameter to be a vma. Any implementations that require the mm can
>>> access it via vma->vm_mm.
>>>
>>> This commit makes the required powerpc modifications. Separate commits
>>> update the other arches and core code, before the actual bug is fixed in
>>> arm64.
>>>
>>> No behavioral changes intended.
>>
>> This patch doesn't build, allthough I have also applied patch 1. Is
>> something missing ?
>>
>>     CALL    scripts/checksyscalls.sh
>>     CC      arch/powerpc/kernel/setup-common.o
>> In file included from arch/powerpc/kernel/setup-common.c:37:
>> ./include/linux/hugetlb.h: In function 'huge_ptep_modify_prot_commit':
>> ./include/linux/hugetlb.h:987:28: error: passing argument 1 of
>> 'set_huge_pte_at' from incompatible pointer type
>> [-Werror=incompatible-pointer-types]
>>     987 |         set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
>>         |                         ~~~^~~~~~~
>>         |                            |
>>         |                            struct mm_struct *
>> In file included from ./arch/powerpc/include/asm/hugetlb.h:13,
>>                    from ./include/linux/hugetlb.h:815:
>> ./arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h:49:45: note: expected
>> 'struct vm_area_struct *' but argument is of type 'struct mm_struct *'
>>      49 | void set_huge_pte_at(struct vm_area_struct *vma, unsigned long
>> addr, pte_t *ptep, pte_t pte);
>>         |                      ~~~~~~~~~~~~~~~~~~~~~~~^~~
>> cc1: all warnings being treated as errors
>> make[4]: *** [scripts/Makefile.build:243:
> 
> Oh, I realised that it requires patch 6 to build properly. This is not 
> good. Your series should be bisectable, that means it must build and run 
> successfully after each patch. Therefore you have to squash patches 1 to 
> 7 all togethers.

Yeah my bad - sorry about that. I thought it would be better to separate the
changes for each arch. But as already suggested by Andrew and Catalin, I'll
squash the first 7 patches into 1 for v2.

> 
> I'll send you comments on the powerpc part in another mail.
> 
> Christophe